Does sugar cause ADHD?

Boy with sugary foods
Boy with sugary foods

The three most prominent features of ADHD are inattention, hyperactivity and impulsivity – and few people without first-hand experience of living with a child with ADHD realise how disruptive this kind of behaviour can be.  

To medicate or not

There are medicines that effectively control ADHD, the most well-known of which are probably Ritalin and Concerta. Many parents, however, prefer to avoid medication, and according to Healthline ADHD medication can cause serious side effects like sleep problems, mood swings, loss of appetite, heart problems and suicidal thoughts or actions.   

Read: Diagnosing ADHD

Although controversial and largely unproven, natural ADHD remedies include exercise, yoga, meditation, massage and dietary supplements. It is also often recommended that people who suffer from ADHD avoid certain foods, food additives and preservatives.

Also controversial is the role of sugar in ADHD.

Sugar is everywhere

Natural sugars have always been present in foods like fruit, vegetables and even milk, but refined sugar is a relatively new addition to the human diet and has only been around for a few hundred years. Nowadays sugar is everywhere and is even added to "normal" foods like bread and spaghetti sauce.

Refined sugar is linked to weight gain and tooth cavities, and is also an empty calorie in the sense that it doesn’t contain vitamins, minerals, fibre and other nutrients. 

Read: 30% empty calories for US kids

In addition, too much sugar can cause reactive hypoglycaemia (a drop in blood sugar after eating), and an article in the Seattle Times describes such a “sugar crash” as “that sudden fatigue, headache or irritability you might feel after eating, oh, a hundred jelly beans”. This happens when high levels of glucose flood the blood, creating sudden spikes and subsequent drops in blood sugar levels. 

Numerous studies

An article in Psychology Today points out that although many studies have investigated the relationship between ADHD and refined sugar and found that sugar doesn’t play a role, many mothers with children that “bounce of the walls” would disagree.

An influential study published in 1985 by Dr Mark Wolraich examined the behaviour of 16 hyperactive boys over a period of three days. The boys received either a sucrose drink or a placebo at regular intervals. The resultant findings were that there was no difference between the behavioural or cognitive actions of the two groups.  

Read: Kids: obesity, hyperactivity, allergies  

Another study, conducted in 1992, involved 35 children described by their mothers as “sugar sensitive”. Although all of the children were given a sugar-free drink, the mothers all rated their children as more hyperactive after they drank the beverage. The study authors subsequently concluded that the problem was not sugar, but "the expectations of the parents".

Yale Scientific mentions two experiments indicating that sugar may at least influence behaviour. A study by Yale researcher, Dr Wesnes, indicated that having a large amount of sugar for breakfast led to a severe deterioration of attention span when compared to having no breakfast or eating whole grain cereal. The other study by Dr Tamborlane, also from Yale, reported that children given sugar had higher levels of adrenaline.

On the other side of the spectrum once again, a 2008/9 Korean study observed no significant association between total volume of simple sugar intake from snacks and ADHD development.

According to BBC Future,the most comprehensive study to date is a meta-analysis carried out in 1995, where the data from the best-designed studies were combined and re-analysed. The studies covered ages from two to thirty, and were "well-designed though fairly small". The results of the meta-analysis were clear, i.e. that sugar could not be shown to affect behaviour or cognitive performance.

Complicated situation

Research into the exact cause of ADHD is ongoing, and attributing this complex condition to one cause is probably a gross oversimplification. According to Mayo Clinic, factors that may be involved in the development of ADHD include: 

  • Genetics: Studies indicate that genes may play a role.
  • Environment: Environmental factors, such as exposure to heavy metals, may increase the risk.
  • Development: Problems with the central nervous system at important moments in a child's development may contribute.

The above-mentioned Psychology Today article suggests a practical test to find out if sugar affects a person's ADHD symptoms. The basic idea is to keep a written log of the child’s behaviour while putting them “on” and “off” sugar for a week at a time for a total period of a month. Comparing the results of the “sugar” and “sugar-free” weeks will give parents a good indication of the effect, if any, sugar has on their child.

Read more:

ADHD: What now?

Taking control of ADHD

Any added sugar is bad sugar

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